Method of adding a liquid fuel to the air blast in a shaft furnace or specifically in a blast furnace



P 21, 1965 SHIN HASHIMOTO ETAL 3,207,597

METHQD OF ADDING A LIQUID FUEL TO THE AIR BLAST IN A SHAFT FURNACE 0RSPECIFICALLY IN A BLAST FURNACE Filed Oct. 8, 1962 Shin HashimofaZensaku Ayuha INVENTORS BY M, Mac/M ATTORNEYS United States Patent Ofice 3,2fi7,597 Patented Sept. 21, 1965 3,207,597 METHOD OF ADDING ALIQUID FUEL TO THE AIR BLAST IN A SHAFT FURNACE R SPECIFI- CALLY IN ABLAST FURNACE Shin Hashimoto and Zensaku Ayuha, Yawata, Fukuoka, Japan,assignors to Yawata Iron 8: Steel Co., Ltd., Tokyo, Japan, a corporationof Japan Filed Oct. 8, 1962, Ser. No. 229,112 Claims priority,application Japan, Oct. 19, 1961, 36/ 37,774 1 Claim. (Cl. 75-42) Thisinvention relates to a method of adding a liquid fuel such as, forexample, a heavy oil or a light oil to the air blast in a shaft furnaceor specifically in a blast furnace.

Generally, in the case of operating a shaft furnace or specifically ablast furnace by adding a liquid fuel to the air blast thereto, theliquid fuel will be atomized with the help of such gaseous medium as airor steam and the atomized liquid fuel together with the gaseous mediumwill be added to the air blast.

In such method, as the gaseous medium for the purpose of atomizing theliquid fuel is mixed into the air blast, there arise certaindifficulties in the operation. For example as a result of mixing-in theair or steam for the atomization, the combusion temperature in front ofthe tuyere is lowered, the calculation of the heatand material-balanceWithin the furnace becomes difficult and the emergency cutoff operationwill be complicated and further there are such disadvantages thatadditional equipment, as an air compressor or a steam generator, isrequired and the longer part of the liquid fuel conduit must be exposedto the air blast or the hot blast.

An object of the present invention is to provide a new method of addinga liquid fuel to the air blast in a shaft furnace or specifically ablast furnace wherein the above mentioned difficulties and disadvantagescan be eliminated.

The method of the present invention comprises jetting liquid fuel into aconduit pipe between an inlet or a tuyere for introducing the air blastinto the furnace and the point where the blast for the inlet isseparated from the blast main pipe without the help of any gaseousmedium so that the jet of liquid fuel may intersect the direction of theflow of the said air blast for atomizing the said liquid fuel and byadjusting one or more of the factors such as the direction of jetting-inthe liquid fuel. the size of the jetting port, the temperature of theliquid fuel and the flow velocity of the air blast at the position ofthe jet, the atomization can be controlled.

According to the present invention, because no gaseous medium for thepurpose of atomizing the liquid fuel is required, the lowering of thecombustion temperature in front of the tuyere will be prevented and theheatand material-balance can be correctly calculated and because noequipment for the said gaseous medium is required the installation costwill be reduced. In addition, the operation of the blast furnace willbecome much simpler. Further, according to the present invention, thelength of the liquid fuel conduit which is exposed to heat can bereduced.

In the present invention, the position of jetting liquid fuels into theair blast is located between the tuyere and the point where the blastfor the tuyere is separated from the blast main pipe so that at least apart of the jetted and atomized liquid fuel may burn before coming tothe combustion zone within the furnace.

In case the flow velocity of the air blast at the point where the liquidfuel is jetted into the air blast is not adapted to the atomization ofthe liquid fuel, the said flow velocity should be adjusted with anadjustable flow-choking device in the proper position.

The pressure of the liquid fuel at the jetting port may be at leastequal to the pressure required to jet-in the fuel against the air blastpressure.

The jetting port may be circular, rectangular, elliptic or of any othershape.

It is not necessary that the air blast contains steam or added oxygenfor the purpose of the operation.

An embodiment of the present invention shall be explained with referenceto the accompanying drawings.

FIGURE 1 illustrates a liquid fuel jetting port based on the principleof the present invention and positioned in the blow pipe of the blasttuyere of a blast furnace.

FIGURE 2 is a detailed view of the jetting port.

The present invention shall be detailed in the following with referenceto the embodiment illustrated in the drawlIlgS.

In the drawings, 1 is a tuyere, 2 is a blow pipe and 3 is a ring whichis provided on the inner periphery of the blow pipe 2 but which will notbe required if the required air blast velocity is available. 4 is aliquid fuel conduit. 5 is a liquid fuel jetting port. The arrow Aindicates the direction of jetting-in the liquid fuel. The arrow Bindicates the direction of the air blast. In order to increase the flowvelocity of the air blast at the point of jetting-in the liquid fuel,the ring 3 is fitted in that part of the blow pipe 2 and its insidediameter D is made to be 130 mm. Under the conditions at whichexperiments were carried out the flow of the air blast was 770 Nm. min.,the pressure of the air blast was 680 g./crn. the flow velocity of theair blast in the part fitted with the ring (which will not be requiredif the required air blast velocity is available) of the blow pipe was220 m./sec., the distance L from the forward end of the tuyere 1 to thepoint of jetting-in the liquid fuel was varied between 200 and 1500 mm.and the point of jetting-in the liquid fuel was made of a heat-resistingsteel such as, for example, SUS 217. The inside diameter of the jettingport was 2 to 4 mm. The angle on to the direction perpendicular to thedirection of the air blast was 0 to 30 directed upstream of the airblast. (See FIGURE 2.) When a heavy oil at C, was jetted at a velocityof 5 to 15 m./ sec. into the air blast under the above mentionedconditions with the above mentioned device, the oil was completelyatomized and introduced into the furnace.

What we claim is:

A method of adding liquid fuel to the air blast for a blast furnace,comprising the steps of constricting the flow of the air blast throughthe blow pipe at a point located at a distance of from 200 to 1500 mm.from the end of the tuyere on the end of the blow pipe to adjust thevelocity of the air blast so that it is at least 220 m./sec., atomizingthe liquid fuel by forcing a stream 3 4 consisting of liquid fuel into ablow pipe at said point References Cited by the Examiner and at an angleto the flow of the air blast which is be- UNITED STATES F tween aperpendicular to the longitudinal axial direction of the blow pipe andto an angle which is 30 from said 325,293 9/85 Weber 2Z6 '29perpendicular in the upstream direction in said blow pipe, 1 22 $g' gsaid stream bein forced into the air blast at a flow velocit S ens 4 g y2,524,476 10/50 Rlchardson 26 629 of 5 to 15 m./sec., and burning a partof the atomized liquid fuel between the point at which the fuel isforced I I into the blow pipe and the tuyere on the end of the blowDAVID REOK Prlmary Examiner pipe. 10 WINSTON L. DOUGLAS, Examiner.

